ErrorResponse 信封的 503 issuer_not_configured;空值/无效值、读取失败、Runtime Pending/Invalid 或事实无法一致应用时返回 503 issuer_runtime_invalid,且不暴露外部登录配置。curl --location '/api/v1/auth/external-providers'[
{
"slug": "string",
"name": "string"
}
]